1. Field of the Invention
The subject invention relates to a sweep unit assembly for use with a roll former.
2. Description of Related Art
Manufacturing apparatuses using a roll former are well known in the prior art and include a series of paired roll dies for progressively deforming and shaping a continuous strip of stock material. For example, roll formers are commonly used to form articles such as metal window or door frames. Each pair of roll dies has a slightly different configuration with a last pair of roll dies having a complementary configuration matching the final desired shape of the article, i.e., the shape of the metal window or door frame. The high speed and continuous nature of roll forming lends itself to economic production of large volume of parts. Hence, roll forming is a desirable manufacturing technique due to the virtually infinite lengths of material and the significant cost reductions as compared to stamping techniques.
In certain applications, it is desirable to have a curved profile imported into the shaped article, i.e., in roof bows and headers for vehicles. Hence, the shaped stock article must be bent or curved along one or more axes as the finished article emerges from the roll former. In order to implement the desired bend or curve, a sweep unit assembly is often utilized. Most prior art sweep unit assemblies are only capable of curving the material in a single direction. An example of a prior art sweep unit assembly of this type is shown in U.S. Pat. No. 4,530,226.
The prior art has also developed sweep unit assemblies that are capable of simultaneously curving the article in two directions to form a compound curve in the article. These sweep unit assemblies, however, are time consuming and difficult to adjust, often fail to impart the desired curves into the article, and are extremely limited in their application.
Further, for both the single and compound curve sweep unit assemblies of the prior art, these units can only curve material having limited tensile and yield strengths. The prior art sweep unit assemblies commonly impart a curve into an article formed of a material having a tensile strength of 40 KSI to 132 KSI and a yield strength of 15 to 20 percent. These strength limitations prevent certain components from being curved. As such, these components cannot be formed on a sweep unit assembly and must be formed by a less efficient stamping technique.
Accordingly, it would be desirable to develop a sweep unit assembly capable of imparting curves into articles formed of materials of greater strengths. Further, it would be desirable to impart a compound curve into virtually any article while avoiding the deficiencies of the prior art assemblies.